The kind of date you take someone on if you're not sure if you want to nail them or not. It's well known that erotic passions are inflamed by mocha.
An analogy of this would be that coffee dates are to real dates what seeing each other is to actually going out.

"What's happening with Jess and Jeff?"
"They're on a coffee date"
"Say no more."

The awkward, yet most common way for young adults to catch up in public. A coffee date is a good way to see someone you need to in a low-key way with a short time frame. Often used when coming home from college for breaks or catching up with old friends found on Facebook.